Put the summary of the bug you're having here

What I expected to happen was...: just play normally
Describe what you thought should happen here

What actually happened was...: Minecraft crashed...
Describe what happened here

Steps to Reproduce:
---- Minecraft Crash Report ----
// Ooh. Shiny.

Time: 12/27/17 1:18 PM
Description: Updating screen events

java.lang.IllegalStateException: failed to create a child event loop
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:88)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:58)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:47)
at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:58)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:77)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:72)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:59)
at oz$1.a(SourceFile:61)
at oz$1.b(SourceFile:58)
at rh.c(SourceFile:10)
at oz.a(SourceFile:152)
at bib.a(SourceFile:2209)
at bol.e(SourceFile:229)
at bol.a(SourceFile:182)
at bol.a(SourceFile:148)
at bjm.a(SourceFile:41)
at bok.a(SourceFile:117)
at blk.k(SourceFile:400)
at bok.k(SourceFile:49)
at blk.q(SourceFile:377)
at bib.t(SourceFile:1625)
at bib.az(SourceFile:1000)
at bib.a(SourceFile:419)
at net.minecraft.client.main.Main.main(SourceFile:123)
Caused by: io.netty.channel.ChannelException: failed to open a new selector
at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:157)
at io.netty.channel.nio.NioEventLoop.<init>(NioEventLoop.java:149)
at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:127)
at io.netty.channel.nio.NioEventLoopGroup.newChild(NioEventLoopGroup.java:36)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:84)
... 23 more
Caused by: java.io.IOException: Unable to establish loopback connection
at sun.nio.ch.PipeImpl$Initializer.run(Unknown Source)
at sun.nio.ch.PipeImpl$Initializer.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at sun.nio.ch.PipeImpl.<init>(Unknown Source)
at sun.nio.ch.SelectorProviderImpl.openPipe(Unknown Source)
at java.nio.channels.Pipe.open(Unknown Source)
at sun.nio.ch.WindowsSelectorImpl.<init>(Unknown Source)
at sun.nio.ch.WindowsSelectorProvider.openSelector(Unknown Source)
at io.netty.channel.nio.NioEventLoop.openSelector(NioEventLoop.java:155)
... 27 more
Caused by: java.net.ConnectException: Connection refused: connect
at sun.nio.ch.Net.connect0(Native Method)
at sun.nio.ch.Net.connect(Unknown Source)
at sun.nio.ch.Net.connect(Unknown Source)
at sun.nio.ch.SocketChannelImpl.connect(Unknown Source)
at java.nio.channels.SocketChannel.open(Unknown Source)
at sun.nio.ch.PipeImpl$Initializer$LoopbackConnector.run(Unknown Source)
... 36 more

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

– Head –
Thread: Client thread
Stacktrace:
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:88)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:58)
at io.netty.util.concurrent.MultithreadEventExecutorGroup.<init>(MultithreadEventExecutorGroup.java:47)
at io.netty.channel.MultithreadEventLoopGroup.<init>(MultithreadEventLoopGroup.java:58)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:77)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:72)
at io.netty.channel.nio.NioEventLoopGroup.<init>(NioEventLoopGroup.java:59)
at oz$1.a(SourceFile:61)
at oz$1.b(SourceFile:58)
at rh.c(SourceFile:10)
at oz.a(SourceFile:152)
at bib.a(SourceFile:2209)
at bol.e(SourceFile:229)
at bol.a(SourceFile:182)
at bol.a(SourceFile:148)
at bjm.a(SourceFile:41)
at bok.a(SourceFile:117)
at blk.k(SourceFile:400)
at bok.k(SourceFile:49)
at blk.q(SourceFile:377)

– Affected screen –
Details:
Screen name: bli
Stacktrace:
at bib.t(SourceFile:1625)
at bib.az(SourceFile:1000)
at bib.a(SourceFile:419)
at net.minecraft.client.main.Main.main(SourceFile:123)

– System Details –
Details:
Minecraft Version: 1.12.2
Operating System: Windows Vista (x86) version 6.0
Java Version: 1.8.0_151, Oracle Corporation
Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
Memory: 75643760 bytes (72 MB) / 286810112 bytes (273 MB) up to 523501568 bytes (499 MB)
JVM Flags: 6 total; -Xmx512M -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
Launched Version: 1.12.2
LWJGL: 2.9.4
OpenGL: AMD Radeon HD 6450 GL version 4.3.12618 Compatibility Profile Context 13.251.0.0, ATI Technologies Inc.
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Probably not. Jar signature remains and client brand is untouched.
Type: Client (map_client.txt)
Resource Packs:
Current Language: Français (France)
Profiler Position: N/A (disabled)
CPU: 2x Intel(R) Core(TM)2 Duo CPU E4400 @ 2.00GHz